webmail green bubble

We can see on some screenshots of the interface webmail a supplementary tab in the list to the left which contains a green bubble.
What can we make with this tab?
What's the version in which we can find it?

It is IM, and it's not been dropped just move back in light of other higher priority items. We still plan to implement it eventually. You can use zmprov to enable it for your account. It doesn't do much today though.

Looking for new beta users -> Co-Founder of Acompli. Previously worked at Zimbra (and Yahoo! & VMware) since 2005.